assembleSemanticsNode method
- SemanticsNode node,
- SemanticsConfiguration config,
- Iterable<
SemanticsNode> children
override
Assemble the SemanticsNode for this RenderObject.
If describeSemanticsConfiguration sets
SemanticsConfiguration.isSemanticBoundary to true, this method is called
with the node
created for this RenderObject, the config
to be
applied to that node and the children
SemanticsNodes that descendants
of this RenderObject have generated.
By default, the method will annotate node
with config
and add the
children
to it.
Subclasses can override this method to add additional SemanticsNodes to the tree. If new SemanticsNodes are instantiated in this method they must be disposed in clearSemantics.
Implementation
@override
void assembleSemanticsNode(
SemanticsNode node,
SemanticsConfiguration config,
Iterable<SemanticsNode> children,
) {
assert(() {
if (child == null && children.isNotEmpty) {
throw FlutterError.fromParts(<DiagnosticsNode>[
ErrorSummary(
'$runtimeType does not have a child widget but received a non-empty list of child SemanticsNode:\n'
'${children.join('\n')}',
),
]);
}
return true;
}());
final List<CustomPainterSemantics> backgroundSemantics = _backgroundSemanticsBuilder != null
? _backgroundSemanticsBuilder!(size)
: const <CustomPainterSemantics>[];
_backgroundSemanticsNodes = _updateSemanticsChildren(_backgroundSemanticsNodes, backgroundSemantics);
final List<CustomPainterSemantics> foregroundSemantics = _foregroundSemanticsBuilder != null
? _foregroundSemanticsBuilder!(size)
: const <CustomPainterSemantics>[];
_foregroundSemanticsNodes = _updateSemanticsChildren(_foregroundSemanticsNodes, foregroundSemantics);
final bool hasBackgroundSemantics = _backgroundSemanticsNodes != null && _backgroundSemanticsNodes!.isNotEmpty;
final bool hasForegroundSemantics = _foregroundSemanticsNodes != null && _foregroundSemanticsNodes!.isNotEmpty;
final List<SemanticsNode> finalChildren = <SemanticsNode>[
if (hasBackgroundSemantics) ..._backgroundSemanticsNodes!,
...children,
if (hasForegroundSemantics) ..._foregroundSemanticsNodes!,
];
super.assembleSemanticsNode(node, config, finalChildren);
}